Bottle making machines are divided into a plurality of sections respectively including a rough mold and a finishing mold, and are installed at a manufacturing site for glass bottles. Bottles of the same type are manufactured all together at each section of the bottle making machines, and thereafter, each manufactured bottle is subjected to a plurality of types of inspections. Each bottle bears a code mark representing a mold number specific to a mold belonging to respective bottle manufacturers in order to control quality and improve productivity, and an inspection system including a reader for reading a code from the code mark and various types of inspection machines is installed at the manufacturing site for glass bottles.
The inspection system prepares inspection result information wherein a mold number read from each bottle is mapped to each type of inspection results for each bottle, and totalize the number of defects detected by each inspection machine using the inspection result information for each type of defects and for each model number. A site worker can check the totalized result using a terminal device in the system, and thus can easily identify molds that generate many defects and take rapid countermeasures including the inspection and repair of a mold.
Conventionally, a code mark representing a mold is usually displayed on the bottom of bottles as an arrangement of projections representing a binary code. However, the projections of the code mark projected from the bottom of bottles may have a negative impact on the inspection of the content therein by a customer after the bottles were filled with the content. Further, a bottle having a significantly elevated bottom may cause the problem that the projections of the code mark cannot be exactly imaged. As such, code marks are often displayed on the outer peripheral surface of a bottle, specifically on the outer peripheral surface of the heel portion of a bottle.
For example, a patent document 1 describes a device capable of reading a code mark represented by the arrangement of projections formed on the outer peripheral surface of a heel portion. The device recognizes code information the code mark shows by generating a signal representing an uneven state in a circumferential direction of the heel portion using an optical sensor and analyzing the signal, while rotating a bottle using a frictional force generated by a frictional roller that is brought into contact with the bottle supported on a table.
A bottle, which bears a code mark using projections on the outer peripheral surface, displays a character string code including digits that coincide with the code mark to allow a person to recognize the code mark. The character string code may include alphabetical letters and so forth representing the manufacturing site in addition to digits representing a mold. The code mark using projections has some standards, and thus a reading program needs to be changed depending on the standard applied to a bottle to be read. It is intended to develop a device capable of reading a mold number from an image acquired by imaging the character string code with a camera in order to avoid such a cumbersome process.
For example, a device disclosed in a patent document 2 is configured such that a bottle displaying embossed characters on the outer peripheral surface of the heel portion is placed on a turn table; a translucent screen is arranged to face the heel portion of the bottle on the turn table; and an illumination device is disposed at a position to face the screen across the bottle. The light emitted from the illumination device passes through the bottle so that an image is projected on the screen. The image is captured with a camera and characters representing a mold number can be recognized on an image generated.